Venus Williams will face a player she inspired to take up tennis after reaching her first Grand Slam quarter-final since 2010 at the Australian Open.
Williams defeated sixth seed Agnieszka Radwanska 6-3 2-6 6-1 at Rod Laver Arena to set up a last-eight clash with American teenager Madison Keys, who had earlier beaten compatriot Madison Brengle in straight sets.
Keys, 19, has made no secret of her admiration for the Williams sisters, although it is something the siblings might not like being reminded of too often.
"Apparently she started playing because she watched Serena and I," said the 34-year-old Venus. "She was watching me in diapers."
Venus' last quarter-final appearance in a Grand Slam came in the US Open in 2010, the year before she was diagnosed as suffering from Sjogren's syndrome, a debilitating autoimmune disease.
Keys was just five-years-old when Venus won the first of her seven Grand Slam singles titles at Wimbledon in 2000 and is relishing the prospect of facing one of her childhood heroes.
"I'm just really excited," she said. "I think it's a huge opportunity for me. I haven't been in this situation before. I'm going to make the most of it. I want to be at the end of the tournament holding the trophy up. That's my goal in the long run.
"I think Venus has helped the sport, especially the women's side with equal prize money. She was a huge part of that. Just watching her is inspirational."
Keys may have to face both Williams sisters if she wants to win the title, with Serena taking on Dominika Cibulkova in the other quarter-final in the top half of the draw.
Top seed Serena had some help from her fans to thank for overcoming another slow start - and a coughing fit - to defeat Spain's Garbine Muguruza 6-3 2-6 6-1.
Serena admitted the shouted advice of one spectator to "use spin" helped her turn the match around, adding: "She (Muguruza) played so well and she did everything she needed to do in the first set.
"I just decided to do my best and stay focused and stay relaxed. She hits the ball really, really big and hard, but someone in the crowd shouted at me to use spin. I did and it really helped me."
Williams struggled with a cough during the match and the 33-year-old said she had been "a little sick the past couple of days". She added: "I've been fighting it with vitamin C and all kinds of stuff. I definitely feel better than I did yesterday."
Novak Djokovic reached an impressive 23rd consecutive Grand Slam quarter-final with a 6-4 7-5 7-5 win over Luxembourg's Gilles Muller at the Australian Open yesterday.
Djokovic is trying to become the second man after Roy Emerson to win five Australian Open titles.